用纸制成的杯子，纸箱和食品包装纸似乎是可以生物降解的，但是许多含有无法堆肥的塑料涂料。尽管可以使用无塑料，可持续的纸产品，但它们通常会让油脂和油通过，削弱纸张并造成混乱。今天，科学家报告说，他们开发了可降解的聚合物涂层，该涂层可以阻止这种渗透，并可能导致新的可生物降解的纸基材料。亚博网站下载
研究人员将在美国化学学会（ACS）的秋季会议上介绍他们的结果。ACS秋季2021年是一场实际举行的混合会议，并于8月22日至26日举行，按需内容将于8月30日至9月提供。30.会议在广泛的科学主题上进行了7,000多个演讲。亚博老虎机网登录
“消费者正在推动更可持续的产品，”该项目首席研究员Matthew Carter博士说。“但是，为一次性应用程序制作完全可降低的纸质产品，例如在自助餐厅获得的三明治包装纸，碗和托盘 - 是一个巨大的挑战，”卡特（Carter）补充说，他正在会议上展示工作。
当前用于一次性纸产品的油性和耐油脂涂料通常包括荧光照或聚烯烃，但这些聚合物在环境上是持续的，无法堆肥。“使常规聚合物有用的一件事是它们的耐用性”他的首席调查员安德鲁·赫吉（Andrew Hejl）博士说，他在陶氏（Dow）与卡特（Carter）合作。这种韧性起源于在聚合过程中形成的稳定的碳碳键，例如一种基于乳胶的房屋油漆，必须持续数年，但在注定要堆肥的纸碗中有问题。
One way to make polymers less durable is to insert degradable linkages to disrupt their carbon-carbon backbones, Carter says. To do so, the researchers turned to a free radical polymerization technique that had been around for years but hadn’t been widely adopted. Noticing a recent resurgence of interest in academia for using this technique with cyclic ketene acetal and vinyl monomers, the Dow team began exploring how to translate this chemistry to an industrial setting. In academia, the reaction was typically carried out in organic solvents, but Dow wanted to switch to water as a “greener” substitute. That was difficult because cyclic ketene acetal monomers are unstable in water, but the researchers addressed that problem by tweaking reaction conditions, including pH, temperature and monomer concentration.
Their reaction mixed the cyclic ketene acetal 2-methylene-1,3-dioxepane and vinyl acetate to form a polymer with ester linkages in the backbone. The team then coated paper with a water-based emulsion of this polymer — a synthetic “latex” unrelated to natural latex rubber, and therefore unlikely to trigger an allergic reaction — and let it dry. They recently reported that the coating provided an effective barrier against oil and grease, and that its ester linkages could break apart in water, quite slowly at neutral pH but faster at higher pH under lab conditions. Now, the researchers are beginning to assess the coating’s degradability under industrially relevant conditions. So far they have shown that microorganisms that are used in industrial composters can help biodegrade the polymer in simulated wastewater.“The concept is to have a long polymer that breaks down into smaller pieces that will ultimately get broken down by microbes into CO2，，，，赫尔说。
其他研究人员和公司也开发了可生物降解的食品服务产品，并使用基于天然材料（例如乳清或壳聚糖）的涂料。亚博网站下载“这些是不错的选择，但是在获得适当价格的性能方面，它们有局限性。”赫尔说。他补充说，一些涂料必须用作非常稀释的溶液，因此必须将大量水蒸发才能干燥。“So there are a lot of potential materials, and I don't think that anything yet has checked off every box.”But the Dow researchers believe their coating might just fill the bill.
“More broadly, if you look at the concept of interrupting a stable carbon-carbon backbone with degradable linkages, that really opens up a lot of opportunities beyond just paper coatings,” Carter says。“Other applications include personal care or home care formulations, like shampoo and floor polish. Many of these materials currently contain synthetic carbon-carbon bond polymers. So this approach could be a powerful way to introduce degradability to new classes of materials in the future.”
The researchers acknowledge support and funding from道琼斯。
Source:https://www.acs.org/